Yes but over the lifetime of a GPU, you'll spend more on power draw than the physical hardware. That's where the savings come from, or at least that's what I've been told.

A V100 costs ~300/yr in electricity. If you are buying at the scale of 100k units, but can price per operation, even by just 10% (for example, by dropping features you don't care about), that's a million dollars of electricity over the lifetime of your hardware.